The impact of alcohol-induced ATF6-mediated ER stress and Golgi disorganization on pro-metastatic glycosylation of integrins in prostate cancer

摘要 前列腺癌（PCa）风险与饮酒之间的联系长期以来一直存在争议。我们最近 在对流行病学数据的广泛评估中发现，自PSA检测时代开始以来， 研究表明，饮酒与前列腺癌风险密切相关。尽管有这种流行病学的支持， 关于酒精与前列腺癌风险、进展和死亡率之间的潜在机制知之甚少。博士 Petrosyan引入了“癌高尔基体”的概念，即高尔基体变得碎片化，导致改变的 糖基化和糖蛋白的运输。此外，这种高尔基体的解体与激活有关 转录因子6（ATF 6）介导的内质网（ER）应激。这导致血浆中 膜（PM）表达的αv整合素异常糖基化的高尔基体糖基转移酶，N- 乙酰葡糖胺转移酶-V（MGAT 5）。重要的是，这些MGAT 5修饰的整联蛋白与 五聚体半乳糖凝集素-3，导致在PM上的保留增加。这反过来又调节了肿瘤细胞的行为， 包括粘附和迁移，其促进前列腺肿瘤向淋巴结和远处转移。 机关我们已经发现，乙醇（EtOH）处理可使高尔基体解体，PCa组织从 重度酗酒者MGAT 5表达和PM整合素αv水平较高。我们建议EtOH促进 通过增加整合素α v介导的PCa进展导致的PCa致死率。肿瘤细胞中整合素αv糖基化改变 预计酒精对高尔基体的破坏作用会加剧高尔基体。初步数据显示， 在乙醇处理的细胞中，整合素αv的PM强度与高尔基体片段数呈正相关 紫杉醇耐药PCa细胞。重要的是，我们发现PCa高尔基体解体是自噬驱动的， 自噬抑制剂羟氯喹（HCQ）可以恢复晚期前列腺癌细胞中紧密的高尔基体。 我们还发现，ATF 6介导的内质网应激导致低糖基化、高甘露糖的表达。 （高分子）整联蛋白通过ER-PM连接到达PM。ATF 6的消耗减少了高分子量 整合素的PM和ER-PM交界处，以及减少ER-PM通信的总数。 我们已经证明了HCQ恢复高尔基体和ATF 6抑制ER应激的协同作用。 在预防原位肿瘤生长和转移方面，这些令人兴奋的数据使我们预计， 联合治疗将降低EtOH给药的促转移作用。我们观察到 在用EtOH和HCQ处理的细胞中挽救了高尔基体形态，这表明， HCQ参与EtOH诱导的高尔基体解体。此外，HCQ恢复PM整合素αv水平 与对照组细胞相比。我们预期HCQ治疗和ATF 6耗竭的组合将有效地减弱 乙醇对前列腺癌侵袭和转移的影响。总的来说，这些数据将揭示以前 酒精促进前列腺肿瘤生长和转移的未知机制，并提供了一个潜在的 有效的治疗策略。

Abstract The link between prostate cancer (PCa) risk and alcohol consumption has long been debated. We recently found in an extensive assessment of the epidemiologic data that, since the onset of the PSA testing era, most studies indicate alcohol consumption is strongly associated with PCa risk. Despite this epidemiologic support, little is known about the underlying mechanisms linking alcohol to PCa risk, progression, and mortality. Dr. Petrosyan introduced the concept of "onco-Golgi," where the Golgi becomes fragmented, resulting in altered glycosylation and trafficking of glycoproteins. Additionally, this Golgi disorganization is linked to activating transcription factor 6 (ATF6)-mediated Endoplasmic Reticulum (ER) stress. This results in increased plasma membrane (PM) expression of αv integrins abnormally glycosylated by Golgi glycosyltransferase, N- acetylglucosaminyltransferase-V (MGAT5). Importantly, these MGAT5-modified integrins form clusters with pentameric Galectin-3, resulting in increased retention on the PM. This, in turn, modulates tumor cell behavior, including adhesion and migration, which promotes prostate tumor dissemination to lymph nodes and distant organs. We have found that ethanol (EtOH) treatment aggravates Golgi disorganization and PCa tissues from heavy alcoholics have higher MGAT5 expression and PM Integrin αv levels. We propose that EtOH promotes PCa lethality by increasing Integrin αv-mediated PCa progression. Altered glycosylation of Integrin αv in the onco- Golgi is expected to be exacerbated by alcohol's disorganizing effect on Golgi. Preliminary data demonstrate a positive correlation between the number of Golgi fragments and the PM intensity of Integrin αv in EtOH-treated docetaxel-resistant PCa cells. Importantly, we have found that PCa Golgi disorganization is autophagy-driven and that the autophagy inhibitor, Hydroxychloroquine (HCQ), restores the compact Golgi in advanced PCa cells. We have also shown that ATF6-mediated ER stress results in expression of underglycosylated, high-Mannose (high-Man) integrins to the PM through ER-PM junctions. Depletion of ATF6 decreases the amount of high-Man integrins on the PM and in ER-PM junctions, as well as reduces the total number of ER-PM communications. We have demonstrated the synergistic effect of Golgi restoration by HCQ and ER stress inhibition by ATF6 depletion in preventing orthotopic tumor growth and metastasis. These exciting data led us to expect that similar combination treatments will decrease the pro-metastatic effects of EtOH administration. We have observed rescued Golgi morphology in cells treated with both EtOH and HCQ, suggesting that Golgiphagy, blocked by HCQ, is involved in EtOH-induced Golgi disorganization. Additionally, HCQ restores the level of PM Integrin αv to that of control cells. We expect that combined HCQ treatment and ATF6 depletion will effectively attenuate the effects of EtOH on PCa aggressiveness and metastasis. Overall, these data will shed light on the previously unknown mechanism of alcohol-promoted prostate tumor growth and metastasis and provide a potentially effective therapeutic strategy.